The h2 protocol (http/2 over TLS/1.2) is the only protocol that the current major browsers support, like Chrome, Firefox, IOS9, Win10. The h2c (http/2 over http and no browser currently supports it) is a non-encrypted protocol that mod_http2 also supports and maybe the browsers will chill out eventually and support it. After all, not everything needs encryption and therefor a waste of resources on both ends of a connection.